Glossary

Fielding independent pitching (FIP)

A pitching metric on the ERA scale built only from strikeouts, walks, hit-by-pitches and home runs, a pitcher's most direct outcomes.

Also called: FIP

Fielding independent pitching estimates what a pitcher's ERA "should" look like based only on the outcomes least influenced by the defense behind them: strikeouts, walks, hit batters and home runs allowed. It deliberately excludes balls put in play that a fielder could catch or misplay.

The formula is FIP = ((13 × HR + 3 × (BB + HBP) − 2 × K) / IP) + constant, where the constant, typically around 3.10, rescales FIP to the same numeric range as league ERA in a given season. This differs from ERA itself, which credits or blames the pitcher for every ball in play, even though team defense and plain luck strongly influence whether those balls become outs or hits, a relationship captured by batting average on balls in play.

Analysts use FIP to judge a pitcher's true skill level separate from the defense fielding behind him and short-term batted-ball luck, and to identify pitchers whose ERA is likely to regress toward their FIP over a larger sample, an application of regression to the mean. The main pitfall is treating FIP as a complete replacement for ERA: FIP assumes league-average results on balls in play, which understates the value of pitchers who reliably induce weak contact, and it ignores baserunner sequencing and inherited runners.

Last reviewed September 22, 2026

In the index now

Related terms

On-base plus slugging (OPS) A baseball hitting stat adding on-base percentage and slugging percentage into a single number summarizing overall production. Batting average on balls in play (BABIP) The batting average on balls put in play, excluding home runs and strikeouts, used to gauge how much luck shaped a batting line. Pythagorean expectation A formula estimating a team's expected win percentage from the points or runs it scores and allows, rather than its actual record. Regression to the mean (in sports) The statistical tendency for unusually good or bad performances to move back toward a player's or team's underlying average. Sabermetrics The empirical, statistics-driven study of baseball performance, valuing measurable production over traditional scouting judgment.

Related guides

How baseball analytics works How sabermetrics grew from box scores to batted-ball physics, what OPS, FIP and BABIP actually measure, and where teams still argue.